-6=3(u-7)-6u

Solution for -6=3(u-7)-6u equation:

Simplifying
-6 = 3(u + -7) + -6u

Reorder the terms:
-6 = 3(-7 + u) + -6u
-6 = (-7 * 3 + u * 3) + -6u
-6 = (-21 + 3u) + -6u

Combine like terms: 3u + -6u = -3u
-6 = -21 + -3u

Solving
-6 = -21 + -3u

Solving for variable 'u'.

Move all terms containing u to the left, all other terms to the right.

Add '3u' to each side of the equation.
-6 + 3u = -21 + -3u + 3u

Combine like terms: -3u + 3u = 0
-6 + 3u = -21 + 0
-6 + 3u = -21

Add '6' to each side of the equation.
-6 + 6 + 3u = -21 + 6

Combine like terms: -6 + 6 = 0
0 + 3u = -21 + 6
3u = -21 + 6

Combine like terms: -21 + 6 = -15
3u = -15

Divide each side by '3'.
u = -5

Simplifying
u = -5